As disclosed in U.S. patent application. No. Ser. 11/482,742, filed on 2006 by the present inventor, a rotatory carrier 3 has a coupling base 31 and a fixing base 32 disposed oppositely on the backside of the rim thereof. Two paired lateral arms 33 are disposed bilaterally on the rotatory carrier 3. A track frame 35 is fixed on the coupling base 31 and the fixing base 32. A sliding slot 351 is formed on the upper portion of the track frame 35, and the front end of the track frame 35 is fixed on the coupling base 31 of the rotatory carrier 3. The track frame 35 is securely screwed on the fixing base 32 via fixing plates 352 that locates on the rearward of the track frame 35. Rotation shafts 36 are securely coupled with the coupling portions 23 on the rearward of a lamp holder 2 so that the lamp holder 2 is axially positioned on the track frame 35 by the rotation shafts 36 so as to axially fix the lamp holder 2 on a rotatory carrier 3.
The lamp bulb is coupled with the inside of the lamp holder in such a manner that the lamp holder has a smaller rotation radius. Accordingly, the lamp bulb has a smaller rotation angle, and the lamp holder is not adaptable for the lamp bulb that has a longer length. What is needed is an improvement which overcomes these and other shortcomings.